In a managed information environment, such as a networked computer infrastructure, cryptographic techniques have been employed for transforming data in a manner indiscernible to an unauthorized interceptor, but efficiently renderable to an intended recipient. Such techniques typically rely on a so-called one-way function, for which computation in the forward direction is relatively, straightforward, but reverse computation based on applying an inverse function are computationally infeasible. One-way functions are typically facilitated by the use of a key that is known to the authorized parties to the message, without which the corresponding inverse function requires substantial computational resources to compute. Early cryptographic techniques, due to the computationally intensive operations required, were typically reserved for encryption and authentication of highly sensitive communications, but modern advances in computational abilities coupled with increased awareness of a need to protect electronically transmitted information have made such cryptographic techniques commonplace.
These and other trends are opening up computing systems to new forms of outsourcing, that is, delegation of computing services to outside entities. Improving network bandwidth and reliability are reducing user reliance on local resources. Energy and labor costs as well as computing system complexity are militating toward the centralized administration of hardware. Increasingly, users employ software and data that resides thousands of miles away on machines and that they themselves do not own. Grid computing, the harnessing of disparate machines into a unified computing platform, has played a role in scientific computing for some years. Similarly, software as a service (SaaS)—loosely a throwback to terminal/mainframe computing architectures—is now a pillar in the Internet-technology strategies of major companies.
Storage is no exception to the outsourcing trend. Online data-backup services abound for consumers and enterprises alike. Amazon® Simple Storage Service, for example, offers an abstracted online-storage interface, allowing programmers to access data objects through web service calls, with fees metered in gigabyte-months and data transfer amounts. Researchers have investigated alternative service models, such as peer-to-peer data archiving, as an emerging trend.